What is pneumonia?
Pneumonia is an infection of one or both lungs, and is usually caused by bacteria, viruses, or fungi. Prior to the discovery of antibiotics, one third of all people who developed pneumonia subsequently died from the infection. Currently, over 3 million people develop pneumonia each year in the United States. Over a half a million of these are admitted to a hospital for treatment. Although most recover, approximately five per cent will die from pneumonia. Pneumonia is the sixth leading cause of death in the United States.

How do people "catch pneumonia?"
Some cases of pneumonia are contracted by breathing in small droplets that contain the organisms that can cause pneumonia. These droplets get into the air when a person infected with these germs coughs or sneezes. In other cases, pneumonia is caused when bacteria or viruses that are normally present in the mouth, throat, or nose inadvertently enter the lung. During sleep it is quite common for people to aspirate secretions from the mouth, throat, or nose. Normally, the body's reflex response (coughing back up the secretions) and immune system will prevent the aspirated organisms from causing pneumonia. However, if a person is in a weakened condition from another illness, a severe pneumonia can develop. People with recent viral infections, lung disease, heart disease, and swallowing problems, as well as alcoholics, drug users and those who have suffered a stroke or seizure are at higher risk for developing pneumonia than the general population.

Once organisms enter the lungs, they usually settle in the air sacs of the lung where they rapidly grow in number. This area of the lung then becomes filled with fluid and pus, as the body attempts to fight off the infection

What are pneumonia symptoms?
Most people who develop pneumonia initially have symptoms of a cold which are then followed by a high fever (sometimes as high as 104 degrees Fahrenheit), shaking chills, and a cough with sputum production. The sputum is usually discolored and sometimes bloody. Patients may become short of breath. Chest pain may develop if the outer aspects of the lung are involved. This pain is usually sharp and worsens when taking a deep breath, known as pleuritic pain.

In other cases of pneumonia, there can be a slow onset of symptoms. A worsening cough, headaches, and muscle aches may be the only symptoms. In some individuals with pneumonia, coughing is not a major symptom because the infection is located in areas of the lung away from the larger airways. At times, the individual's skin color may change and become dusky or purplish (a condition known as "cyanosis") due to their blood being poorly oxygenated.

Children and babies who develop pneumonia oftentimes do not have any specific signs of a chest infection, but develop a fever, appear quite ill, and become lethargic. Elderly people may also have few symptoms with pneumonia.

How is pneumonia diagnosed?
Pneumonia may be suspected when the doctor examines the patient with a stethoscope, and hears coarse breathing or crackling sounds in a portion of the chest. There may be wheezing, or the sounds of breathing may be faint in a particular area of the chest.

• A chest x-ray is usually ordered to confirm the diagnosis of pneumonia.
• Sputum samples can be collected and examined under the microscope. If the pneumonia is caused by bacteria, they can often be detected by this examination. A sample of the sputum can be grown in special incubators, and the bacteria can then be identified. It is important to understand that the sputum specimen must contain little saliva from the mouth and be delivered to the laboratory fairly quickly. Otherwise, overgrowth of non-infecting bacteria may predominate.
• A blood test that measures white blood cell count (WBC) may be performed. An individual’s white blood cell count can often give a hint as to the severity of the pneumonia and whether it is caused by bacteria or a virus.
• Bronchoscopy is a procedure in which a thin, flexible, lighted viewing tube is inserted into the nose or mouth. The breathing passages can then be directly examined by the doctor, and specimens from the infected part of the lung can be obtained.
  Sometimes, fluid collects around the lung as a result of the inflammation from pneumonia. This fluid is called a pleural effusion. If the amount of fluid is large enough, it can be removed by inserting a needle into the chest cavity and withdrawing it with a syringe. This procedure is called a thoracentesis. In some cases, this fluid can become severely inflamed (parapneumonia effusion) or infected (empyema) and may need to be removed by more aggressive surgical procedures.

How is pneumonia treated?
Early treatment with antibiotics can cure most bacterial pneumonia. Along with antibiotics, individuals should get plenty of rest, eat a proper diet, and take medication to relieve the cough. In some severe cases patients may need supplemental oxygen. There is no antibiotic treatment for viral pneumonia, however; the other recommendations are effective for both bacterial and viral pneumonia.

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